Dual carburetor



June l0, 1947. c. L. MARTIN 2,421,800

\ I DUAL cmm'ron L V FiledSepL 4, 1943` 3 Sheets-Sheet 1 24V/.VM

C. L. MARTIN DUAL CARBURETOR Filed Sept. 4, 1943 June 10, 1947.

5 Sheets-Sheet 2 IN-VENTOR. CHARLES L.MART|N BY June l0, 1947.

c: l.. MARTIN DUAL CARBURETGR Filed sept.' 4. 194s 3 Sheets-Sheet 3 INVENTOR. CHARLES L. MARTIN f7/KM' llatented June 10, 1947 DUAL CARBURETOR Charles L. Martin, Overland, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application September 4, 1943, Serial No. 501,331

(ci. 12a-127) r 11'Claims.

This invention relates to internal combustion engines and' consists particularly in novel means for controlling the supply of combustible mixture thereto.

There have been suggestions for providing a multi-cylinder internal combustion engine, particularly of the automotive type, with dual fuel intake conduits having throttle valves capable of independent of selective action for separately controlling'groups of cylinders. This is of particular advantage in an automotive engine in which considerable economy can be attained by operating less than all the cylinders when only a portion of the power capacity of the engine is being utilized. However, whenv one throttle valve is closed to cut off a group of cylinders, a suction drag is created in these cylinders, the over-coming of which uses a part of 'the power output of the operating cylinders. The waste of power and fuel has been overcome by providing an extra suction breaking valve which admits air to the non-firing or auxiliary cylinders, or by fully opening the throttle valve on the non-firing side. The latter means requires, of course, a device other than the throttle valve for cutting off the fuel supply.

. An object of the present invention is to provide simplified means for controlling the supply oi.' fuel to one of the mixture conduits or to a portion of the cylinders while permitting the-now` of air to the auxiliary cylinders at all times so that a suction drag is not set up when some of the cylinders are cut out.

A further object is to provide a novel device of the above character including means causing substantial initial opening of the fuel control valve to insure the prompt formation of a combustible mixture with the air owing through the mixture conduit.

Another object is to provide an auxiliary fuel control device, operated by the throttle controlthe automotive type with fuelsupply manifolds and a carburetor embodying the present invention.

Fig. 2 isa side view of a carburetor and controls, partly sectioned, showing theparts in the positions assumed with the engine idling, certain parts in broken lines being shown in the positions they assume when the engine is at rest.

Fig. 3 is a vertical transverse section through the carburetor, the parts being in the same positions as in Fig. 2.

Fig. 4 is aview similar to Fig. 2, but showing the auxiliary fuel valve about to be tripped" during opening movement of the main throttle.

Fig. 5 is a view similar to Fig. 3, but showing the auxiliary fuel valve just after tripping by continuedv main throttle opening.

Fig. 6 is a similar View showing the main throttle and auxiliary fuel valve held wide open fo'r full speed operation. And K Fig. 'l is a view similar to Fig. 4,f but showing the auxiliary fuel valve trippedas the result of lowering of the suction resulting from increased power demands upon the engine.

Fig. 8 is a 'detail inside View of the valve snap.

The engine represented in Fig. 1 comprises a block I0 having cylinders designated I to 8, in-

auxiliary I elusive, each having an intake and an exhaust port with suitable valves (not shown). A pair of separate intake manifolds Il and I2 connect, respectively, the intake ports of cylinders I, 2, 1 and 8 and 3, 4, 5 and 6 with the outer or main and inner, or auxiliary'barrels of the carburetor, generally indicated at I3. The usual exhaust manifold, connecting the exhaust ports of the ,cylinders to the exhaust pipe, is omitted.

ling the constantly running cylinders, with means permitting partial independent closing of the main throttle valve, after the auxiliary fuel valve is opened, and partial independent opening of the main throttle as the auxiliary valve is closed,V

whereby the sudden change in power, as the auxiliary cylinders start to operate and cut out, may be dampened.

These objects and other more detailed objects hereafter appearing are attained by the structure illustrated in the accompanying drawings in which: l.

Fig. 1 is a diagrammatic top view representing an eight cylinder internal combustion `engine of The carburetor, shown in greater detail in Fig.

3, is of the downdraft, double barreled type including a common air inlet horn I4, a main mixture conduit I5 having multiple venturis 'I6 and a butterfly throttle valve I1, and an-auxiliary mixture conduit I8 having multiple venturis I9, but having no control at its outlet portion, corresponding with main throttle Il. A central partition, including parts 20 and 2l extends the length of the carburetor between the mixture conduit, choker valve 22 being cut as at 23 to accommodate upper partition 2|. The choker valve may be controlled by any suitable manual i or automatic control attached to shaft 24.

Adjacent tnermixturerconduits 1s a fue1`=ow1 21 within which fuel is maintained at a substantially lconstant level by the usual float and needle valve mechanism (only the iloat being shown) and profuel bowl communicates with an vupwardly in- 15 and terminates in main nozzle 35 discharging into the smallest or innermost venturi i5. An'interf when the engine starts Ato run and the throttle` rigid with throttle `eration, as to the position in Fig. 4, link 64 will be moved leftwardly, swinging'lever. 5l clockwise until right hand ear'lil thereon engages` lever arm 55 rigid with valve shaft 5I'. Upon slight connected idling system' includesjpassages 35, 31 l0` 56 will pass over-center, whereupon spring 186 will and 38 connecting the main nozzle passage` With idling ports 39 and Ml located adjacent the edge of throttle valve l1 when closed. V

A second metering'orice 65 located in the clined auxiliary fuel passage t5 which terminates in a nozzle tl discharging into the smallest or innermost venturi" l5 in auxiliary mixture conduit I3. Orifice t5 is controlled by a metering lpin t8 operated by a Centrally pivoted lever t9 20 connected at its inner endby a link 5U to throttle arm 32.l ABoth the metering pin operating linkages are arranged to lift the supported plus as throttle Il is opened. to increase the effective openings in the metering orifices and enrich the 25 mixture supplied by the nozzles. 'I'he calibration of main metering pin 29 does not necessarily conform with that of auxiliary pin d5.

Pivotally mounted within the smallest venturi I3, onA a shaft 5i, is a small butterfly-type valve 30 52 which controls the discharge from auxiliary fuel nozzle S1. The operating mechanism for this valve is better shown in Figs, 2, 4, 5, 6,'7 and 8. Rigid with valve shaft 5I outside the barrel is a lever having opposite arms 55 and 56. A 35 second lever 5l is pivoted to the upper extremity of arm 56, on pin 58, and has a central transverse slot 59 receiving the extremity of valve shaft 5| The lower portion of lever 5l has invfardly extending ears 65 and 5I at opposite sides 40 thereof, and is connected by a pin 6'2 to links 63 and 34. Link 64 has a longitudinal sloi-l 65 at its opposite extremity receiving a. pin 65 carried by 'an arm 61 rigid with main throttle shaft 33. ,A second arm`68 on the same end-of the 45 throttle shaft has an aperture 63 in its extremity for connection to suitable accelerator linkage extending in the usual manner to the drivers compartment. Arm 68 has a lug 10 carrying a throttle adjusting screw for engaging a 50 fixed stop 1| on the carburetor barrel.

A cylinder mounted on a bracket 'I6 adjacent the carburetor barrel slidably receives a pisy ton Il constantly urged to the left by a coiled spring 18. A threaded cap 19 on the end of the 55 cylinder provides for adjusting the spring. The cap has e. tapped hole I80 for attachment of a tube 8| 'connecting the cylinder to main intake manifold Il. A rod 32 extends leftwardly froml the piston through a loosely fitting hole 83 in the 60 left hand end of the cylinder and has a; pin 84 received in a slot "85 in the right hand end of previously mentioned link 63.

Overlapping levers 56 and 5l constitute a snap i action device,`- the over-center action being en- 65 forced by a tension spring 86 stretched between i pin 58` and a pin 81 rigid with the carburetor body. .Iv This mechanism operates as follows:

. The rest position of piston 11 and main throt- 70 tle I1 is represented by the broken line positions of these parts in Fig. 2. To start the engine,

throttlell is moved to a somewhat more open position, the lost motion in slot 65 permitting this Without affecting the remainderof the linkage. 75

cause it to snap to the position in Fig. 5, in which shaft 5l is at the left hand side of slot 59 and valve lever is rotated clockwise so as to substantially open small valve 52. Thereafter, valves 52 and il move openward together.

The distance between ears and 6l, and slot 55 lprovide for limited movement of small valve 52 under the influence of varying suction, as applied to piston l1, When main throttle His in intermediate position.- Fig. 7 is similar to Fig. 4 except that small valve 52 has been tripped by suction, main .throttle il remaining in 'a fixed position. Thus, it is possible for the auxiliary mixture conduit to cut in and cut out by snap action in accordance with load requirements.

In Fig. 6, the main throttle il and auxiliary fuel valve 52 are both held in wide open position for full speed operation. During the first part of the closing of throttle Il, pin 'on the throttle of fuel from auxiliary nozzle 46 and provides for lconstant passage of air to inner or auxiliary cylinders 3, t, 5 and 6 regardless of whether they are firing or not. The snap action of this valve prevents the supplying of fuel at an insuiiicient rate to form a proper firing charge with the air passing around and through the venturis. Slot 651m link 64 permits partial closing of main throttle Il, when the auxiliary cylinders start to operate and also partial opening of the throttle as the auxiliary cylinders cut out so as to reduce the resultant sharp change of power. The ultimate effect of this is to permit the operator to to obtain a smooth variation in torque during transfer from four to eight cylinder operation as would occur when the auxiliary cylinders start to operate since noidling system is provided f or low speed operation of these cylinders.

The invention may be modified in various, respects as will occur to those skilledlin the art and the exclusive use of all modifications as come within they scope of the appended claims is contemplated.

I claim:

1. Inan internal combustion engine, main and auxiliary fuel mixture conduits individually feedcontinued throttle opening movement, lever 55,

arm 6l is shiftedto the lower end of slo't 55 and Y `ndividually feeding the engine, a main fuel nozzle :lischarging into said main conduit, a throttle controlling the mixture discharged from said main conduit, a Venturi tube mounted in said auxiliary conduit and spaced from the walls thereof, an auxiliary fuel nozzle discharging into said tube, and a butterfly valve pivoted in said tube and controlling the passage of air lthrough said tube and the discharge of fuel from said auxiliary nozzle.

3. In an internal combustion engine, separate main and auxiliary fuel mixture intake conduits individually feeding the engine, a throttle valve in said main conduit and a fuel nozzle discharging thereinto, multiple Venturi tubes in said auxiliary conduit, an auxiliary fuel nozzle discharging into the smallestv of said tubes, and a butterfiy throttle pivoted in said last-mentioned tube and controlling the passage of air through said tube and the discharge of fuel from said auxiliary nozzle, the space around said smallest Venturi tube providing for constant feeding of air to the engine regardless of the emission of fuel from said auxiliary nozzle.

4'. An internal combustion engine as specified in claim 3 in which each of said mixture conduits supplies a separate cylinder or group of cylinders.

5. In an internal combustion engine, separate main and auxiliary mixture conduits each supplying a'separate cylinderor group of cylinders,

mounted in and controlling the passage of air through said inner tube and, thereby, the emission of fuel from said auxiliary nozzle, and valve operating means comprising a lost ,motion connection between said throttle and said valve for oper' ating said valve responsive to movements of said throttle. f

8. An internal combustion engine as described in claim 7 in which said valve operating means further includes means responsive to engine suction for operating said valve within the limits vof said lost motion connection.

a main fuel nozzle and a manual throttle fory one of said conduits, multiple Venturi tubes in the other conduit, an auxiliary fuel nozzle, discharging into the inner one of said tubes, a valve mounted on said inner tube and controlling the,

passage of air therethrough and thereby, the

emission of fuel from said auxiliary nozzle, and operating means for said valve including a snap action device for causing substantial initial opening of said valve to insure prompt formation of a combustible mixture with the air passing through and around said innerVenturi tube.

6. In an internal combustion engine, a pair of mixture conduits each supplying a separate cylinder or group of cylinders, a fuel nozzle and a manual throttle for one of said conduits, multiple Venturi tubes in the other conduit, an auxiliary fuel nozzle discharging into the inner one of said tubes, a valve mounted on and controlling the passage of air through-said inner tube and, thereby, the emission of fuel from said auxiliary nozzle, and means connecting said manual throttle and said valve for operating said valve responsive to movements of said throttle, said means including asnap action device for causing substantial initial opening and rapid final closing of said valve to insure formation ofa combustible mixture with the fuel `discharged from said auxiliary nozzle, and saidmeans also including a lost motion element whereby opening movement of said throttle. may be continued after said snap action of said valve.

7. fIn an internal combustion engine, a pair of fuel mixture conduits individually feeding the engine, a main fuel nozzle and a manual throttle'for oneof said conduits, multiple Venturi tubes in the other conduit, an auxiliary fuel nozzle discharging into the inner one of said tubes. a valve 9. An internal combustion engine as described in claim 7 in which said valve operating means further includes a snap action device incorporated with said lost motion connection for causing substantial initial opening and rapid final closing of said valve to insure formation of a combustible mixture with air passing through and around said inner Venturi tube whenever said auxiliary nozzle is discharging.

10. An internal combustionengine as described in claim 7 in which said valve' operating means further includes 'an engine suction responsive device for operating said valve Within the limits of said lost-motion connection, and a, snap-alction device, for causing substantial initial open-` ing and rapid final closing of said valve to introlling said inner Venturi tube'to control the discharge of fuel from said nozzle, and manual means to operate said valve including a snap action device for insuring fully closed or substan i tially open positioningof said valve so that sufcient fuel. is discharged by said nozzle to form a combustible mixture with the air entering through and around said inner Venturi. tube at all times that said nozzle is discharging.

i CHARLES L. MARTIN,

aEFEaENoEs CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Overaasen Apr. 1, 1924 

